A high dynamic range amplifier circuit for amplifying pixel signals of an imager device is disclosed. The amplifier circuit uses a read-out scheme based on a charge recycling approach, where a pixel signal is first amplified with a low gain during a first amplification phase T1, and then the amplifier output is immediately recycled and the pixel signal amplified with a higher gain during a second amplification phase T2.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An method for amplifying a signal, comprising: capturing a set of initial charges in response to receiving an input signal; generating a first intermediate signal from said set of initial charges; first amplifying said first intermediate signal at a first gain level to produce a first output signal; after said first amplifying, restoring said set of initial charges; after said restoring, generating a second intermediate signal from said set of restored initial charges, and second amplifying said second intermediate signal at a second gain level to produce a second output signal.
2. The method of claim 1 , wherein said first intermediate signal is equal to said second intermediate signal.
3. The method of claim 1 , wherein said second gain level is greater than said first gain level.
4. The method of claim 1 , wherein said input signal, said first intermediate signal, said second intermediate signal, said first output signal, and said second output signal are each differential signals.
5. The method of claim 1 , wherein said first amplifying is performed by passing said first intermediate signal through an amplifier and said second amplifying is performed by passing said second intermediate signal through said amplifier.
6. The method of claim 5 , further comprising: before said first amplifying, resetting said amplifier; and after said second amplifying, resetting said amplifier.
7. The method of claim 5 , wherein said amplifier is not reset between said first amplifying and said second amplifying.
8. An amplifier, comprising: a first circuit for storing a set of input signals as a set of initial charges; a second circuit, said second circuit comprising: an amplification device, coupled to said first circuit; and a switching circuit, coupled to said amplification device; wherein said switching circuit can be configured to be in a first state which causes said amplification device to output a first output signal by amplifying, with a first gain, an intermediate signal received from said initial charges stored in said first circuit, a second state which causes said second circuit to restore said initial charges in said first circuit, and a third state which causes said amplification device to output a second output signal by amplifying, with a second gain, said intermediate signal.
9. The amplifier of claim 8 , further comprising: a controller, coupled to said second circuit, for setting said switching circuit into said first, second, and third states.
10. The amplifier of claim 9 , wherein said controller is configured to set said switching circuit into said first state before setting said switching circuit into said second state.
11. The amplifier of claim 10 , wherein said controller is configured to set said switching circuit into said second state before setting said switching circuit into said third state.
12. The amplifier of claim 8 , wherein said second gain is greater than said first gain.
13. The amplifier of claim 10 , wherein said controller is configured to reset said amplification device before said switching circuit is set to said first state.
14. The amplifier of claim 13 , wherein said controller is configured to reset said amplification device after said switching circuit is set to said third state.
15. The amplifier of claim 14 , wherein said controller is configured to not reset said amplification device between said first and third states of said switching circuit.
16. The amplifier of claim 8 , wherein said amplification device is a differential amplifier.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
June 15, 2004
November 22, 2005
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